US4588943A - Instrument for measuring the moisture content of dielectric objects - Google Patents

Instrument for measuring the moisture content of dielectric objects Download PDF

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Publication number
US4588943A
US4588943A US06/597,360 US59736084A US4588943A US 4588943 A US4588943 A US 4588943A US 59736084 A US59736084 A US 59736084A US 4588943 A US4588943 A US 4588943A
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United States
Prior art keywords
instrument
electrode
measuring
capacitance
capacitance measuring
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
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US06/597,360
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English (en)
Inventor
Friedrich Hirth
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GANN MESS- U REGELTECHNIK A Co OF GERMANY GmbH
Bayer AG
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Bayer AG
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Assigned to GANN MESS- U. REGELTECHNIK GMBH, A COMPANY OF GERMANY reassignment GANN MESS- U. REGELTECHNIK GMBH, A COMPANY OF GERMANY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: HIRTH, FRIEDRICH
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
    • G01N27/226—Construction of measuring vessels; Electrodes therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
    • G01N27/223—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance for determining moisture content, e.g. humidity

Definitions

  • the invention relates generally to an instrument for measuring moisture content.
  • the invention relates to an instrument for measuring the moisture content of dielectric substances, especially dielectric solids.
  • a known instrument for measuring the moisture content of dielectric objects has a housing which accommodates a measuring circuit designed to detect small changes in capacitance.
  • a measuring capacitor capable of generating a diverging voltage field extends from the housing.
  • the measuring capacitor in a conventional instrument of this type consists of a plurality of parallel or concentric electrodes.
  • the electrode arrangement includes both active and grounded electrodes and is designed in such a manner that the active electrodes alternate with or are located adjacent to the grounded electrodes. In other words, each active electrode is located between two grounded electrodes.
  • the electrodes are placed against the object.
  • Conventional instruments of the type under consideration are designed on the assumption that the spacing between the electrodes must be smaller than the dimensions of the object. It is believed that virtually the entire voltage field of the measuring capacitor then penetrates into the object.
  • the depth of penetration of the voltage field into the object is highly unsatisfactory.
  • the field strength decreases significantly within a few millimeters.
  • structural components consisting of synthetic resins may exhibit a non-uniform moisture distribution when used under extreme conditions since they may develop hairline cracks or pores which can trap water. If a moisture determination on such a structural component is made at an inner surface thereof, any moisture which may, for instance, have accumulated in hairline cracks at the outer surface cannot be detected. The same applies, for example, to moisture determinations performed on wood where a non-uniform moisture distribution along the thickness develops during drying.
  • Another object of the invention is to provide an instrument of the type outlined above which is particularly well-suited for determining the moisture content of dielectric solids and is capable of detecting moisture at greater depths than conventional instruments.
  • the capacitance measuring means includes a capacitance measuring circuit having first and second terminals for connection with respective electrodes which cooperate to cause the generation of measuring signals during moisture determination.
  • the capacitance measuring means further includes an active first electrode which is connected with the first terminal.
  • the capacitance measuring means is devoid of a cooperating electrode for the first electrode and the second terminal is designed for connection with ground which constitutes a second electrode during moisture determination and cooperates with the first electrode to cause the generation of measuring signals.
  • the support means may comprise a housing for the capacitance measuring circuit.
  • the latter is preferably designed so as to be capable of detecting small changes in capacitance.
  • the first or active electrode may constitute or form part of a measuring capacitor.
  • the measuring capacitor is favorably designed so that a diverging voltage field may be generated at or in the region of the active electrode.
  • the capacitance measuring means preferably projects from the support means.
  • the active electrode may here be located at the end of the capacitance measuring means remote from the support means.
  • an active electrode is physically present while a grounded electrode for cooperation with the active electrode is absent.
  • An instrument according to the invention for measuring the moisture content of dielectric substances enables a diverging voltage field of maximum size and maximum depth of penetration to be generated. This makes it possible to measure the moisture content of a body having a very non-uniform moisture distribution more accurately than heretofore.
  • the moisture measuring instrument of the invention is particularly well-suited for determining the moisture content of a solid dielectric object.
  • the active electrode prefferably small as compared to the object undergoing moisture determination. This further increases the depth of penetration of the diverging voltage field used for measurement of the moisture content.
  • the capacitance measuring means includes an elongated, electrically conductive member having a first end which is secured to and a second end which is remote from the support means.
  • the active electrode is mounted at the latter end of the elongated member.
  • the elongated member is preferably in the form of a metallic, rod-like element. This embodiment makes the instrument easier to handle and permits the instrument to be used in a tilted or inclined position.
  • the active electrode is spherical or semispherical or resembles a spherical calotte.
  • FIG. 1 is a schematic plan view of a prior art instrument designed to measure the moisture content of dielectric objects and having a cone-like electrode arrangement;
  • FIG. 2 is a schematic perspective view of an instrument according to the invention for measuring the moisture content of dielectric substances.
  • FIG. 3 schematically illustrates a measuring circuit for the instrument of FIG. 2.
  • the reference numeral 31 identifies an instrument according to the prior art for measuring the moisture content of dielectric objects.
  • the instrument 31 has a housing 32 which accommodates a non-illustrated measuring circuit.
  • the measuring circuit is connected with a non-illustrated high frequency voltage generator as well as with an indicator 33 located at the front of the instrument 31.
  • the measuring circuit is further connected with a measuring capacitor arrangement 34 which is designed to generate a diverging voltage field and is disposed at the back of the instrument 31.
  • the measuring capacitor arrangement 34 comprises two active electrodes 36 which are connected with one terminal of the measuring circuit.
  • the measuring capacitor arrangement 34 further includes three additional electrodes 37 which are connected with the other terminal of the measuring circuit and are grounded. Each of the active electrodes 36 is located between two cooperating grounded electrodes 37.
  • the electrodes 36 and 37 are placed against the object.
  • the spacing between the electrodes 36 and 37 is smaller than the thickness of the object.
  • a knob 38 is provided to activate the instrument 31.
  • FIG. 2 illustrates an instrument 11 according to the invention for measuring the moisture content of dielectric substances.
  • the instrument 11 is particularly well-suited for measuring the moisture content of dielectric solids.
  • the instrument 11 includes a housing or support means 12 which carries capacitance measuring means.
  • the capacitance measuring means includes a measuring capacitor arrangement 14 which is designed to generate a diverging voltage field for measuring purposes.
  • the capacitance measuring means further comprises a conventional measuring circuit 25 which is schematically illustrated in FIG. 3. As also shown in FIG. 3, the measuring circuit 25 is connected with a high frequency voltage source 26.
  • the measuring circuit 25 is accommodated inside the housing 12.
  • the measuring circuit 25 is connected with and is designed to detect small capacitance variations in the measuring capacitor arrangement 14.
  • the housing 12 has a front wall 19 which is provided with a cutout for window 15.
  • An indicator 13 is mounted on the housing 12 behind the window 15 and is visible through the latter. As illustrated in FIG. 3, the indicator 13 is connected with the measuring circuit 25 so that the indicator 13 may indicate capacitance changes which occur in the measuring capacitor arrangement 14.
  • the housing 12 has a lateral wall 22.
  • the measuring capacitor arrangement 14 includes an electrically conductive rod 20 which projects from the housing 12 and is mechanically secured to the lateral wall 22.
  • the rod 20, which is preferably metallic, is normal to the lateral wall 22.
  • the measuring capacitor arrangement 14 further includes a capacitor having an active electrode 16.
  • the electrode 16 comprises or is constituted by a spherical calotte or sphere 21 composed of metal.
  • the sphere 21 is mounted at the end of the rod 20 remote from the housing 12.
  • the active electrode 16 is electrically connected with one terminal of the measuring circuit 25 or voltage source 26.
  • FIG. 3 also shows by phantom lines radiation from the active electrode 16 that the latter is designed to generate a diverging voltage field for measuring purposes.
  • the length of the rod 20 is selected in such a manner that a slight inclination of the instrument 11 suffices to bring the electrode 16 into contact with an object to undergo moisture determination.
  • the electrode 16 is dimensioned so as to be small relative to an object which is to have its moisture content determined.
  • the capacitance measuring means 14,25 is devoid of a cooperating electrode for the active electrode 16, that is, the capacitance measuring means 14,25 does not have an electrode which acts in conjunction with the active electrode 16 to generate signals during moisture determination. Stated differently, a cooperating electrode for the active electrode 16 is not physically or structurally present in the capacitor of the measuring capacitor arrangement 14. Instead, the cooperating electrode for the active electrode 16 is constituted by electrically conductive ground.
  • the electrode 16 is connected with one terminal of the measuring circuit 25.
  • the other terminal of the measuring circuit 25 is electrically connected with a metallic plate 23.
  • the plate 23 forms part of the front wall 19 of the housing 12 and constitutes a ground of the housing 12.
  • the metallic plate 23 is disposed on that side of the window 15 which is remote from the measuring capacitor arrangement 14 and serves as a cover for the measuring circuit 25 inside the housing 12.
  • a button 18 passes through the cover plate 23 and functions to activate the moisture measuring instrument 11.
  • FIG. 3 illustrates that the measuring circuit 25 comprises a reference capacitor having a reference capacitance C V .
  • FIG. 3 further illustrates by phantom lines the capacitances which arise during moisture determination. The latter capacitances are represented by equivalent circuit elements.
  • the capacitance C M represented by an equivalent circuit element is the measured capacitance of the object undergoing moisture determination.
  • the capacitance C E represented by an equivalent circuit element is the capacitance generated between the measuring instrument 11 and ground, that is, between ground and an operator who touches the cover plate 23 constituting a ground of the instrument 11.
  • the capacitance C G represented by an equivalent circuit element is the capacitance generated between ground and the object undergoing moisture determination. It may be assumed that the capacitances C E and C G are each substantially larger than C M .
  • the reference capacitance C V of the reference capacitor in the measuring circuit 25 equals the capacitance of the air.
  • the dielectric constant is then equal to one and the moisture measuring instrument 11 is balanced.
  • the instrument 11 reads zero when it is held in air and the operator touches the metallic cover plate 23 while depressing the button 18. If an object is brought into the diverging voltage field of the active electrode 16 so that the object contacts the electrode 16, the instrument 11 indicates the difference in the dielectric constants of the air and the object. This, in turn, is a measure of the moisture content of the object since the dielectric constant of the object changes with moisture content.
  • the active electrode 16 of the measuring capacitor may comprise two or more spheres which are arranged at a distance from the housing 12.
  • the different spheres are preferably mounted in such a manner as to be capable of contacting an object undergoing moisture determination simultaneously.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
US06/597,360 1983-08-31 1984-04-06 Instrument for measuring the moisture content of dielectric objects Expired - Fee Related US4588943A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19833331305 DE3331305A1 (de) 1983-08-31 1983-08-31 Dielektrisches feuchtemessgeraet
DE3331305 1983-08-31

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US4588943A true US4588943A (en) 1986-05-13

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Cited By (31)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4860753A (en) * 1987-11-04 1989-08-29 The Gillette Company Monitoring apparatus
US5030918A (en) * 1989-11-17 1991-07-09 Modern Controls, Inc. Portable gauge for measuring thickness variations of thin plastic film
GB2210693B (en) * 1987-10-02 1991-10-23 Scanflow Systems Ltd A portable moisture measuring instrument
USD368310S (en) 1994-09-01 1996-03-26 Microline Technologies, Inc. Skin analyzer
US5853543A (en) * 1997-01-27 1998-12-29 Honeywell-Measurex Corporation Method for monitoring and controlling water content in paper stock in a paper making machine
US5891306A (en) * 1996-12-13 1999-04-06 Measurex Corporation Electromagnetic field perturbation sensor and methods for measuring water content in sheetmaking systems
US5928475A (en) * 1996-12-13 1999-07-27 Honeywell-Measurex, Corporation High resolution system and method for measurement of traveling web
US5938593A (en) * 1996-03-12 1999-08-17 Microline Technologies, Inc. Skin analyzer with speech capability
US5944955A (en) * 1998-01-15 1999-08-31 Honeywell-Measurex Corporation Fast basis weight control for papermaking machine
US6006602A (en) * 1998-04-30 1999-12-28 Honeywell-Measurex Corporation Weight measurement and measurement standardization sensor
US6072309A (en) * 1996-12-13 2000-06-06 Honeywell-Measurex Corporation, Inc. Paper stock zeta potential measurement and control
US6076022A (en) * 1998-01-26 2000-06-13 Honeywell-Measurex Corporation Paper stock shear and formation control
US6080278A (en) * 1998-01-27 2000-06-27 Honeywell-Measurex Corporation Fast CD and MD control in a sheetmaking machine
US6087837A (en) * 1996-12-13 2000-07-11 Honeywell-Measurex Compact high resolution under wire water weight sensor array
US6086716A (en) * 1998-05-11 2000-07-11 Honeywell-Measurex Corporation Wet end control for papermaking machine
US6092003A (en) * 1998-01-26 2000-07-18 Honeywell-Measurex Corporation Paper stock shear and formation control
US6099690A (en) * 1998-04-24 2000-08-08 Honeywell-Measurex Corporation System and method for sheet measurement and control in papermaking machine
GB2347220A (en) * 1999-02-23 2000-08-30 Rynhart Research Limited Moisture meter which may be adapted for use with different materials
US6149770A (en) * 1998-04-14 2000-11-21 Honeywell-Measurex Corporation Underwire water weight turbulence sensor
EP1089071A1 (en) * 1999-09-28 2001-04-04 General Electric Company Material for improved sensitivity of stray field electrodes
US6341522B1 (en) 1996-12-13 2002-01-29 Measurex Corporation Water weight sensor array imbedded in a sheetmaking machine roll
US20040140902A1 (en) * 2003-01-19 2004-07-22 Staples Peter Ethan Wireless soil moisture meter network
US20050119785A1 (en) * 2001-03-21 2005-06-02 Signature Control Systems Process and apparatus for improving and controlling the vulcanization of natural and synthetic rubber compounds
US20050127925A1 (en) * 2003-12-10 2005-06-16 Staples Peter E. Moisture sensor
US20050173820A1 (en) * 2001-03-21 2005-08-11 Signature Control Systems Process and apparatus for improving and controlling the curing of natural and synthetic moldable compounds
US20060213278A1 (en) * 2005-03-28 2006-09-28 Arms Steven W Strain gauge with moisture barrier and self-testing circuit
US7676953B2 (en) 2006-12-29 2010-03-16 Signature Control Systems, Inc. Calibration and metering methods for wood kiln moisture measurement
USD733592S1 (en) * 2013-06-07 2015-07-07 Rockwool International A/S Moisture sensor and controller
USD733593S1 (en) * 2013-06-07 2015-07-07 Rockwool International A/S Moisture sensor and controller
USD734183S1 (en) * 2013-06-07 2015-07-14 Rockwool International A/S Moisture sensor and controller
USD764321S1 (en) * 2015-04-14 2016-08-23 Farnaz Zand Moisture sensing apparatus

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4007813A1 (de) * 1990-03-12 1991-09-19 Bernd Kellerberg Geraet zur pruefung des durchfeuchtungsgrades von windeln
DE4302367A1 (de) * 1993-01-28 1994-08-04 Rwe Energie Ag System zur indirekten Ermittlung kritischer Zustände von zustandsabhängig Gase entwickelnden Stoffen, Anlagenteilen ect.
DE19536766A1 (de) * 1995-10-02 1997-04-03 Somos Gmbh Verfahren zur Bestimmung spezifischer Materialcharakteristiken
DE19538145C2 (de) * 1995-10-13 1998-11-05 Engler Winfried Dipl Ing Fh Verfahren zur Bestimmung der Materialfeuchte eines rieselfähigen Materials (z.B. Erdboden, Torf, Kompost, Sand usw.) im Hochfeuchtebereich
DE19710591A1 (de) * 1997-03-14 1998-09-17 Engler Winfried Dipl Ing Fh Verfahren und Vorrichtung zur berührungslosen Messung der Materialfeuchte im Hochfeuchtebereich
DE102018003062A1 (de) 2018-04-14 2019-10-17 Loba Gmbh & Co. Kg Vorrichtung zum Feststellen des Trocknungsgrades von Auftragprodukten für Fußböden und deren Beläge

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US2428700A (en) * 1943-09-17 1947-10-07 Wolgen Company Capacitative feed-back device for electrical testing
US3559052A (en) * 1968-07-17 1971-01-26 Eaton Yale & Towne Pushbutton moisture meter for determining moisture content in grain
US3609735A (en) * 1968-12-03 1971-09-28 Harris Intertype Corp Inductive-capacitive probe in machine for handling sheetlike material
US3651505A (en) * 1969-03-24 1972-03-21 Schmall Margit Capacitive distance measuring
US3714560A (en) * 1970-11-17 1973-01-30 Ralston Purina Co Electrical apparatus for measurement of moisture content by measurement of radio frequency power absorption utilizing a power limiting capacitor
US3879644A (en) * 1970-04-27 1975-04-22 Drexelbrook Controls Probe responsive to conditions of material

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Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2428700A (en) * 1943-09-17 1947-10-07 Wolgen Company Capacitative feed-back device for electrical testing
US3559052A (en) * 1968-07-17 1971-01-26 Eaton Yale & Towne Pushbutton moisture meter for determining moisture content in grain
US3609735A (en) * 1968-12-03 1971-09-28 Harris Intertype Corp Inductive-capacitive probe in machine for handling sheetlike material
US3651505A (en) * 1969-03-24 1972-03-21 Schmall Margit Capacitive distance measuring
US3879644A (en) * 1970-04-27 1975-04-22 Drexelbrook Controls Probe responsive to conditions of material
US3714560A (en) * 1970-11-17 1973-01-30 Ralston Purina Co Electrical apparatus for measurement of moisture content by measurement of radio frequency power absorption utilizing a power limiting capacitor

Cited By (46)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2210693B (en) * 1987-10-02 1991-10-23 Scanflow Systems Ltd A portable moisture measuring instrument
US4860753A (en) * 1987-11-04 1989-08-29 The Gillette Company Monitoring apparatus
US5030918A (en) * 1989-11-17 1991-07-09 Modern Controls, Inc. Portable gauge for measuring thickness variations of thin plastic film
USD368310S (en) 1994-09-01 1996-03-26 Microline Technologies, Inc. Skin analyzer
US5938593A (en) * 1996-03-12 1999-08-17 Microline Technologies, Inc. Skin analyzer with speech capability
US5928475A (en) * 1996-12-13 1999-07-27 Honeywell-Measurex, Corporation High resolution system and method for measurement of traveling web
US5891306A (en) * 1996-12-13 1999-04-06 Measurex Corporation Electromagnetic field perturbation sensor and methods for measuring water content in sheetmaking systems
US6341522B1 (en) 1996-12-13 2002-01-29 Measurex Corporation Water weight sensor array imbedded in a sheetmaking machine roll
US6072309A (en) * 1996-12-13 2000-06-06 Honeywell-Measurex Corporation, Inc. Paper stock zeta potential measurement and control
US6087837A (en) * 1996-12-13 2000-07-11 Honeywell-Measurex Compact high resolution under wire water weight sensor array
US6204672B1 (en) 1996-12-13 2001-03-20 Honeywell International Inc System for producing paper product including a compact high-resolution under wire water weight sensor array
US5853543A (en) * 1997-01-27 1998-12-29 Honeywell-Measurex Corporation Method for monitoring and controlling water content in paper stock in a paper making machine
US5944955A (en) * 1998-01-15 1999-08-31 Honeywell-Measurex Corporation Fast basis weight control for papermaking machine
US6092003A (en) * 1998-01-26 2000-07-18 Honeywell-Measurex Corporation Paper stock shear and formation control
US6076022A (en) * 1998-01-26 2000-06-13 Honeywell-Measurex Corporation Paper stock shear and formation control
US6080278A (en) * 1998-01-27 2000-06-27 Honeywell-Measurex Corporation Fast CD and MD control in a sheetmaking machine
US6149770A (en) * 1998-04-14 2000-11-21 Honeywell-Measurex Corporation Underwire water weight turbulence sensor
US6099690A (en) * 1998-04-24 2000-08-08 Honeywell-Measurex Corporation System and method for sheet measurement and control in papermaking machine
US6126785A (en) * 1998-04-24 2000-10-03 Honeywell-Measurex Corporation System and method for sheet measurement and control in papermaking machine
US6168687B1 (en) 1998-04-24 2001-01-02 Honeywell-Measurex Corporation System and method for sheet measurement and control in papermaking machine
US6323659B1 (en) 1998-04-29 2001-11-27 General Electric Company Material for improved sensitivity of stray field electrodes
US6006602A (en) * 1998-04-30 1999-12-28 Honeywell-Measurex Corporation Weight measurement and measurement standardization sensor
US6086716A (en) * 1998-05-11 2000-07-11 Honeywell-Measurex Corporation Wet end control for papermaking machine
GB2347220A (en) * 1999-02-23 2000-08-30 Rynhart Research Limited Moisture meter which may be adapted for use with different materials
GB2347220B (en) * 1999-02-23 2003-12-31 Rynhart Res Ltd A moisture meter
US6340892B1 (en) * 1999-02-23 2002-01-22 Rynhart Research Limited Hand-held digital moisture meter with memory and communications
EP1089071A1 (en) * 1999-09-28 2001-04-04 General Electric Company Material for improved sensitivity of stray field electrodes
US7167773B2 (en) 2001-03-21 2007-01-23 Signature Control Systems Process and apparatus for improving and controlling the curing of natural and synthetic moldable compounds
US20050119785A1 (en) * 2001-03-21 2005-06-02 Signature Control Systems Process and apparatus for improving and controlling the vulcanization of natural and synthetic rubber compounds
US7433755B2 (en) 2001-03-21 2008-10-07 Signature Control Systems, Inc. Controlling the curing of a rubber compound
US20050173820A1 (en) * 2001-03-21 2005-08-11 Signature Control Systems Process and apparatus for improving and controlling the curing of natural and synthetic moldable compounds
US20070185611A1 (en) * 2001-03-21 2007-08-09 Signature Control Systems, Inc. Controlling the Curing of a Rubber Compound
US7245985B2 (en) 2001-03-21 2007-07-17 Signature Control Systems Process and apparatus for improving and controlling the vulcanization of natural and synthetic rubber compounds
US6975236B2 (en) 2003-01-19 2005-12-13 Blue Clover Design, Llc Wireless soil moisture meter network
US20040140902A1 (en) * 2003-01-19 2004-07-22 Staples Peter Ethan Wireless soil moisture meter network
US20050127925A1 (en) * 2003-12-10 2005-06-16 Staples Peter E. Moisture sensor
US20100300210A1 (en) * 2004-03-29 2010-12-02 Arms Steven W Cover for Protecting Component from Shear Force
US8499628B2 (en) 2004-03-29 2013-08-06 Lord Corporation Cover for protecting component from shear force
US20060213278A1 (en) * 2005-03-28 2006-09-28 Arms Steven W Strain gauge with moisture barrier and self-testing circuit
US7461560B2 (en) * 2005-03-28 2008-12-09 Microstrain, Inc. Strain gauge with moisture barrier and self-testing circuit
US7676953B2 (en) 2006-12-29 2010-03-16 Signature Control Systems, Inc. Calibration and metering methods for wood kiln moisture measurement
US8104190B2 (en) 2006-12-29 2012-01-31 Signature Control Systems, Inc. Wood kiln moisture measurement calibration and metering methods
USD733592S1 (en) * 2013-06-07 2015-07-07 Rockwool International A/S Moisture sensor and controller
USD733593S1 (en) * 2013-06-07 2015-07-07 Rockwool International A/S Moisture sensor and controller
USD734183S1 (en) * 2013-06-07 2015-07-14 Rockwool International A/S Moisture sensor and controller
USD764321S1 (en) * 2015-04-14 2016-08-23 Farnaz Zand Moisture sensing apparatus

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Publication number Publication date
DE3331305A1 (de) 1985-03-14
DE3331305C2 (enrdf_load_stackoverflow) 1992-06-04

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